1. Field of the Invention
This invention relates to a stereo optical system pair for a stereo endoscope system which has right and left optical channels.
2. Description of the Related Art
The following references relate to optical system for stereo endoscopes: U.S. Pat. No. 5,527,263, U.S. Pat. No. 5,522,789, U.S. Pat. No. 5,577,991, U.S. Pat. No. 5,743,846, and Japanese Patent publication No. H6-59196. The following reference relates to optical system which enables adjustment of magnification for endoscopes: U.S. Pat. No. 4,976,522. The last five patents above are commonly assigned as the present application.
Endoscopic robot surgery system continues progressing remarkably. Since the robot surgery system enables highly precise treatment, an endoscope system for the robot surgery system is desired to have stereoscopic imaging and high image quality in order to give surgeons depth perception and detail structure information of an object being observed. It is very important to guarantee matching right and left images for stereo endoscope systems which have right and left optical channels. If a stereo endoscope system consist of endoscope components and camera head components, it is desirable that stereo matching quality of each of all the endoscope products and all the camera head products be guaranteed independently to maintain interchangeability between the components in the stereo endoscope system.
The following are basic optical properties regarding stereo matching, which is to be guaranteed for stereoscopic imaging in general: (A) magnification matching; (B) focus matching; (C) image X-Y shifting matching; and (D) image rotation matching.
Adjustment structures and methods of the matching properties depend on the framework of optical design. An issue to be considered initially in design procedure is how to obtain magnification matching. In order to satisfy magnification matching by adjustment in the assembling process, it is necessary that the right or left optical system be capable of varying magnification which is used to remove magnification difference between right and left channels. Furthermore, it is desired that focus position shift be as small as possible while magnification is varying, in order to reduce dependency of magnification matching adjustment on focus matching adjustment. Such dependency makes magnification measurement difficult in magnification adjustment process, and increases cycles of alternating magnification adjustment and focus adjustment.
In a structure using zoom optical units as shown in U.S. Pat. No. 5,522,789 for this purpose, production cost is likely higher and body size is likely larger because of existing cam mechanism of the zoom optical unit. In a structure having no magnification matching adjustment, as shown in U.S. Pat. No. 5,527,263, it is required to reduce manufacturing error of magnification in each optical channel sufficiently. In order to satisfy this requirement, all the optical and related mechanical components must be manufactured with higher precision than normally required. It is impossible or impractical to apply such requirement for all stereo endoscope systems which have various specifications and cost targets.